Compression assembly for forming rolls

ABSTRACT

A compression assembly for applying consistent pressure to the material being formed into a continuous tube. The pressure is applied to at least one of a pair of forming rolls of a tube mill during the operation thereof.

CROSS-REFERENCE TO RELATED APPLICATION

[0001] This application is a continuation-in-part application of andclaims the benefit of U.S. patent application Ser. No. 10/127,392 filedon Apr. 22, 2002, hereby incorporated herein by reference which claimsthe benefit of U.S. provisional patent application Serial No.60/285,563, filed Apr. 20, 2001.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to the production ofcontinuous seam-welded tubes or pipes and, more particularly, to acompression assembly to cause the forming rolls of a tube mill to applyconsistent pressure across the surface of the material being formed suchas, for example, a continuous strip of steel.

[0004] 2. Description of the Prior Art

[0005] Roll forming machines or tube mills are well known in the art foruse in manufacturing seam-welded tubes. The tube forming processinvolves the shaping of flat stock into a tube with a substantiallycylindrical cross section and applying pressure to the circumferentialwalls of the tube to form the final product. The material being formedis “cold worked” to produce a material of desired diameter and wallthickness.

[0006] Cold working has the undesirable effect of increasing the yieldpoint of the tube material resulting in work hardening. For normal uses,work hardening is an acceptable side effect of the tube manufacturingprocess. With the increased popularity of hydroforming in the vehiclemanufacturing area, however, work hardening has become an undesirableside effect. Hydroforming is a process where water is used to pressurizethe tubing during the final bending processes, thereby reducing wallthinning and wrinkling. Tubing which is bent through the utilization ofthe hydroforming process is typically used for complex shapes requiringstrong structural characteristics such as automobile frames.Hydroforming requires a lower yield point material in order to becapable of being bent into the complex shapes. If an increase in theyield point occurs during the tube forming process, hydroforming becomesmore difficult.

[0007] Roll forming machines or tube mills currently used are comprisedof means for applying pressure to the material being formed. Thepressure is applied by hydraulic or spring pressure conveying devicesthat operate independently of one another. Because of the independentinteraction, uneven pressure is often applied to the material beingworked resulting in excessive cold working of that portion of thematerial. Therefore, the uneven application of pressure results in anincreased yield point in the tubing material.

[0008] An object of the present invention is to produce a compressionsystem that reduces the effect of increasing the yield point in thematerial being formed.

[0009] Another object of the invention is to produce a system for tubemills for applying consistent pressure to the forming rolls during theprocess of producing continuous seam welded tubes.

SUMMARY OF THE INVENTION

[0010] The above, as well as other objects and advantages of theinvention, may be readily achieved by a tube mill including a formingroll section having at least one pair of cooperating forming rollsincluding a rear stand; a front stand spaced from the rear stand; anupper forming roll; an upper spindle supporting the upper forming roll;a lower forming roll cooperating with the upper forming roll; a lowerspindle supporting the lower forming roll; a first bearing means forrotatingly supporting the upper spindle; a second bearing means forrotatingly supporting the lower spindle; and means for mounting thefirst bearing means and the second bearing means on the rear stand andthe front stand and applying constant pressure between the upper formingroll and the lower forming roll.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The objects and advantages of the invention will become readilyapparent to those skilled in the art from the following detaileddescription of an embodiment of the invention when read in the light ofthe accompanying drawings, in which:

[0012]FIG. 1 is an elevational end view partially in section of the rearand front stands of a forming roll section of a tube mill;

[0013]FIG. 2 is a right side elevational view of the forming rollsection illustrated in FIG. 1; and

[0014]FIG. 3 is a schematic view of a hydraulic system for controllingthe pressure fluid applied to the forming rolls illustrated in FIGS. 1and 2.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0015] The specification, claims, and drawings of copending U.S. patentapplication Ser. No. 10/127,782 filed Apr. 22, 2002 is incorporatedherein by reference.

[0016] Referring to the drawings, there is illustrated a compressionassembly for forming rolls, incorporating the features of the invention.

[0017] More specifically, there is illustrated in FIGS. 1 and 2 a rearstand assembly 10 and a front stand assembly 12 of a typical formingroll section of a tube mill of the type wherein a continuous length ofstrip stock, generally referred as skelp, is introduced at the inlet endof the mill and is caused to be passed through a series of sections ofcooperating rolls which function to gradually form the flat strip ofmetal into a tube wherein the abutting edges of the formed strip areresistance welded to form a continuous tube. The continuous tube isfinally cut into predetermined lengths and off-loaded from the mill forsubsequent shipment to the ultimate users.

[0018] The diameter and wall thickness of the finished tube isdetermined by the gauge and width of the skelp being formed as well asthe diameter and cross-sectional configuration of the cooperating rollsof the mill. The section of the mill illustrated in FIGS. 1 and 2 isgenerally referred as the forming section where the skelp is introducedafter being broken down or formed slightly in a breakdown section. Theforming section employs at least one section of a cooperating pair offorming rolls 14 and 16. The forming roll 14 is referred to as the upperforming roll and the lower forming roll 16 is referred to as the lowerforming roll. As clearly apparent from FIG. 1, the upper forming roll 14has a convex cross section, while the lower forming roll 16 has aconcave cross section. The skelp 18 is shown between the cooperatingouter surfaces of the forming rolls 14 and 16.

[0019] The upper forming roll 14 and the lower forming roll 16 aremounted on separate power drives for the upper and lower spindles 20 and22, respectively. The opposite ends of the spindles 20 and 22 arejournaled in suitable bearings in the rear stand 10 and the spaced apartfront stand 12. One end of the upper spindle 20 is journaled in abearing 24 which, in turn, is mounted in the rear stand 10, and theother end is journaled in a bearing 26 which, in turn, is mounted in thefront stand 12. One end of the lower spindle 22 is journaled in abearing 28 which, in turn, is mounted in the rear stand 10, and theother end is journaled in a bearing 30 which, in turn, is mounted in thefront stand 12.

[0020] In order to apply the desired pressure to the forming rolls, thebearings 24 and 26 which support the upper spindle 20 and the associatedupper forming roll 14 are affixed to pressure fluid actuated cylinders32 and 34, respectively. The cylinders 32 and 34 are suitably mounted tothe rear and front stands 10 and 12 as illustrated in FIGS. 1 and 2.Further, the cylinders 32 and 34 are provided with depending piston rods36 and 38, respectively, which, in turn, are provided with suitablefittings connected to respective bearings 24 and 26.

[0021] The bearings 28 and 30 are adjustable in a vertical directionindependently of the cylinders 32 and 34 and the respective piston rodsand fittings. The adjustment of the bearings 24, 26 is effected bysuitably positioned rack and pinion assemblies 40 and 42. The rack andpinion assembly 40 for effecting movement of the bearing 24 is mountedto the rear stand, and the rack and pinion assembly 42 for effectingmovement of the bearing 26 is mounted to the front stand. Concommitantmovement of the bearings 24 and 26 to accept forming roll members ofdifferent diameters is achieved by coupling the pinions of theassemblies 40 and 42 by a connecting shaft 44.

[0022] While there are a number of various systems that could be used toapply pressure fluid to the cylinders 32 and 34, the system illustratedin FIG. 3 has been found to be satisfactory. It will be noted that inthe illustrated system pressure fluid is uniformly introduced from apower source to the cylinders 32 and 34 to selectively cause theassociated pistons to move in unison. Also, other types of pressuretransducers may be use, such as for example, springs. The objective ofthe transducers is to consistently transmit energy from one system toanother and finally to the strip stock being formed.

[0023] In accordance with the provisions of the patent statutes, thepresent invention has been described in what is considered to representits preferred embodiment. However, it should be understood that theinvention can be practiced otherwise than as specifically illustratedand described without departing from its spirit or scope.

What is claimed is:
 1. In a tube mill for the production of continuousseam-welded tubes including a forming roll section having at least onepair of cooperating forming rolls comprising: a rear stand; a frontstand spaced from said rear stand; an upper forming roll; a lowerforming roll cooperating with said upper forming roll; an upper spindlesupporting said upper forming roll; a lower spindle supporting saidlower forming roll; first bearing means for rotatingly supporting saidupper spindle; second bearing means for rotatingly supporting said lowerspindle; and means for mounting said first bearing means to said rearstand and said front stand and applying consistent pressure between saidupper forming roll and said lower forming roll.
 2. The invention definedin claim 1 wherein said means for mounting includes a pressure fluidactuated motor.
 3. The invention defined in claims 2 wherein saidpressure fluid actuated motor includes a cylinder having an internallymounted piston and an associated piston rod extending therefrom.
 4. Theinvention defined in claim 3 wherein said piston rod is coupled to saidfirst bearing means.
 5. The invention defined in claim 2 including adrive for actuating said bearing means independently of said pressurefluid actuated motor.
 6. The invention defined in claim 2 wherein saidpressure fluid actuated motor is a hydraulic motor.
 7. A forming rollassembly for a tube mill for the production of continuous seam weldtubes comprising: a pair of spaced apart stands; a pair of cooperatingforming rolls for receiving strip stock therebetween to be formed into atube; bearings for journaling said forming rolls in said stands; and apressure transducer for applying consistent pressure to at least one ofsaid forming rolls to maintain consistent pressure on the strip stocktravelling between said forming rolls.
 8. A forming roll assembly for atube mill for the production of continuous seam welded tubes from acontinuous supply of strip stock comprising: a pair of spaced apartstands; a pair of cooperating forming rolls for receiving the stripstock therebetween to be formed into a tube; a spindle having oppositeends for supporting each of said forming rolls; bearings for rotatablysupporting the ends of said spindles in respective ones of said stands;and pressure transducer for applying consistent pressure to at least oneof said forming rolls to maintain consistent pressure on the strip stocktravelling between said forming rolls.